A friend of mine did a lot of this on his bike. This might help or may not, but I asked him to send some info on it and here what got him to use this method:
Here's the email that inspired me to try it this way. I can say that it works like a charm. If it's aluminum and not magnesium/aluminum, it'll polish up like chrome. If not, it may be a waste of time. Once it's all looking good then I've been told the best cleaner protectant out there is a product called boms-away. The way people talked about it, I had to give it a try. I'm expecting to get it today or in the near future, so I don't have anything to offer as to how well it works. I can tell you that it cost a pretty penny. About $20 with shipping. Anyway, I heard that you only need to apply it every 6mos. That's the best that I've heard for aluminum yet. On a side note, I found that I almost mistaken pitting for the protective coating on the aluminum wearing out. If it's the part has a coating on it, then gasket remover will take care of it. Then check if it's pitted, if not, just use polish and s kip the sanding. Here's the email and technique for removing pits.
So far I've done my fork legs and risers. I'll tell you what worked just
fine for me:
The parts were pitted. On the fork legs I started with 400-grit sandpaper,
then 600, 800, and 1000, then Simichrome polish. When I have time I'll use
some 1500 then 2000-grit, then more Simichrome. This is called
color-sanding" when done for a paint job. This provides a
finish indistinguishable from chrome. There are products you can spray on
(www.eastwoodco.com) to keep the aluminum looking the way you polished it,
but I haven't tried that yet.
I used all the grades of paper wet (except the very coarse ones), and
sanded by hand with a rubber pad. Make sure you're using wet/dry
paper. You could use some type of wheel on a flex shaft I suppose, but I
prefer wet-sanding. the more grit sizes you use, the better job you'll
get, and it's actually easier in the long run. In other words, do n't skip
from 400 to 800 or 600 to 1000. Also, sand in one direction with a given
grit, then sand in the other direction (crossways) with the next
grit. When the scratches from the previous grit disappear, move on to the
next, again sanding crossways to the grit you just used. This is very
effective in assuring that you get _all_ the scratches out. When you get
up around 1000 grit put a few drops of dish detergent in your sanding water.
BTW, my risers were forged aluminum plated with chrome. They were so bad
I peeled the chrome off with my pocket knife, and the pitting was so bad I
started with 80-grit. But it was well worth it, and is one of the few things I
can do at my kitchen table since it's freaking 10 degrees outside
